means A medium blue-green color, sitting between blue and green on the spectrum.

from The color is named after the bird — the teal, a small freshwater duck with a striking blue-green stripe near its eye. The duck's name came first, an English word dating back centuries (and possibly imitative of its piping call), and only much later, around the early 20th century, did people start using 'teal' for the shade itself. So the color borrowed its name from a bird that wore it best.